U.S. patent application number 10/793022 was filed with the patent office on 2005-09-08 for methods and apparatus for printing conductive thickfilms over thickfilm dielectrics.
Invention is credited to Casey, John F., Dove, Lewis R..
Application Number | 20050195052 10/793022 |
Document ID | / |
Family ID | 34887632 |
Filed Date | 2005-09-08 |
United States Patent
Application |
20050195052 |
Kind Code |
A1 |
Dove, Lewis R. ; et
al. |
September 8, 2005 |
Methods and apparatus for printing conductive thickfilms over
thickfilm dielectrics
Abstract
In one embodiment, a plurality of thickfilm dielectric layers
are printed on a substrate, with each successive layer being
printed over a previous layer, and with each layer having sloped
walls. After printing a first subset of the plurality of thickfilm
dielectric layers, a first conductive thickfilm is printed over at
least the walls of the first subset of dielectric layers. Then,
after printing a second subset of the plurality of thickfilm
dielectric layers, a second conductive thickfilm is printed over
the second subset of dielectric layers (with the first and second
conductive thickfilms being electrically coupled).
Inventors: |
Dove, Lewis R.; (Monument,
CO) ; Casey, John F.; (Colorado Springs, CO) |
Correspondence
Address: |
AGILENT TECHNOLOGIES, INC.
Legal Department, DL429
Intellectual Property Administration
P.O. Box 7599
Loveland
CO
80537-0599
US
|
Family ID: |
34887632 |
Appl. No.: |
10/793022 |
Filed: |
March 3, 2004 |
Current U.S.
Class: |
333/238 ;
333/246 |
Current CPC
Class: |
H05K 2201/09154
20130101; Y10T 29/49155 20150115; H05K 1/092 20130101; H05K 3/4667
20130101; H05K 2201/09981 20130101; H01L 21/4867 20130101; H01P
3/088 20130101; H01L 21/4857 20130101; H05K 1/0221 20130101; Y10T
29/49156 20150115 |
Class at
Publication: |
333/238 ;
333/246 |
International
Class: |
H01P 003/08 |
Claims
What is claimed is:
1. A method, comprising: printing a plurality of thickfilm
dielectric layers on a substrate, with each successive layer being
printed over a previous layer, and with each layer having sloped
walls; after printing a first subset of the plurality of thickfilm
dielectric layers, printing a first conductive thickfilm over at
least the walls of the first subset of dielectric layers; and after
printing a second subset of the plurality of thickfilm dielectric
layers, printing a second conductive thickfilm over the second
subset of dielectric layers, wherein said first and second
conductive thickfilms are electrically coupled.
2. The method of claim 1, further comprising, forming a conductor
on the first subset of dielectric layers.
3. The method of claim 2, wherein the first conductive thickfilm is
also printed over a surface of the first subset of dielectric
layers, and wherein the conductor is formed by etching the
conductor in the first conductive thickfilm.
4. The method of claim 2, further comprising, polishing a top
surface of the first and second subsets of dielectric layers, prior
to printing each of the conductive thickfilms.
5. The method of claim 2, further comprising, coupling a shunt
component to the conductor.
6. The method of claim 5, wherein the shunt component is a
diode.
7. The method of claim 5, wherein the shunt component is a
capacitor.
8. The method of claim 1, further comprising, printing the
plurality of thickfilm dielectric layers over a conductor.
9. The method of claim 1, wherein the plurality of thickfilm
dielectric layers comprises additional subsets of dielectric
layers, and wherein an additional conductive thickfilm is printed
on at least the walls of each additional subset.
10. The method of claim 1, wherein the first subset of dielectric
layers comprises at least two dielectric layers.
11. The method of claim 1, wherein the second subset of dielectric
layers comprises at least two dielectric layers.
12. The method of claim 1, wherein the dielectric layers comprise
KQ dielectrics.
13. The method of claim 1, further comprising, printing the
plurality of dielectric layers on a ground plane, wherein each of
the conductive thickfilms are electrically coupled to the ground
plane.
14. A microwave circuit, produced by: printing a plurality of
thickfilm dielectric layers on a substrate, with each successive
layer being printed over a previous layer, and with each layer
having sloped walls; after printing a first subset of the plurality
of thickfilm dielectric layers, printing a first conductive
thickfilm over the first subset of dielectric layers; etching the
first conductive thickfilm to form i) a conductor on a surface of
the first subset of dielectric layers and ii) a ground on walls of
the first subset of dielectric layers; and after printing a second
subset of the plurality of thickfilm dielectric layers over the
conductor, printing a second conductive thickfilm over the second
subset of dielectric layers, wherein the second conductive
thickfilm is electrically coupled to the ground walls on the first
subset of dielectric layers.
15. The microwave circuit of claim 14, further produced by,
coupling a shunt component to the conductor.
16. The microwave circuit of claim 14, wherein the first subset of
dielectric layers comprises at least two dielectric layers.
17. The microwave circuit of claim 14, wherein the second subset of
dielectric layers comprises at least two dielectric layers.
18. The microwave circuit of claim 14, wherein the dielectric
layers comprise KQ dielectrics.
19. The microwave circuit of claim 14, further produced by,
printing the plurality of dielectric layers on a ground plane,
wherein each of the conductive thickfilms are electrically coupled
to the ground plane.
20. A microwave circuit, produced by: forming a conductor on a
substrate; printing a plurality of thickfilm dielectric layers over
the conductor, with each successive layer being printed over a
previous layer, and with each layer having sloped walls; after
printing a first subset of the plurality of thickfilm dielectric
layers, printing a first conductive thickfilm over at least the
walls of the first subset of dielectric layers; and after printing
a second subset of the plurality of thickfilm dielectric layers,
printing a second conductive thickfilm over the second subset of
dielectric layers, wherein said first and second conductive
thickfilms are electrically coupled.
Description
BACKGROUND OF THE INVENTION
[0001] Using current thickfilm printing techniques, it is difficult
to print a conductive thickfilm over a structure or topology
thicker than about 10 mils. Thus, when a conductor is bounded above
and below by thickfilm dielectrics, each of the dielectrics is
limited to a thickness of about 5 mils so that it is possible to
print a thickfilm ground shield over the dielectric structure.
However, limiting the thickness of the dielectrics that bound a
conductor typically places limits on the conductor itself. For
example, if one desires to build a transmission line structure
having a given impedance, bounding a conductor with dielectrics of
a given height and dielectric constant will dictate the width of
the conductor. While such a "width limit" is sometimes irrelevant,
there are times when a width limit is smaller than desired. For
example, in one application, a conductor "width limit" was smaller
than a width of a shunt component that an engineer wanted to couple
into a transmission line structure.
SUMMARY OF THE INVENTION
[0002] One aspect of the invention is embodied in a method that
comprises printing a plurality of thickfilm dielectric layers on a
substrate, with each successive layer being printed over a previous
layer, and with each layer having sloped walls. After printing a
first subset of the plurality of thickfilm dielectric layers, a
first conductive thickfilm is printed over at least the walls of
the first subset of dielectric layers. Then, after printing a
second subset of the plurality of thickfilm dielectric layers, a
second conductive thickfilm is printed over the second subset of
dielectric layers (with the first and second conductive thickfilms
being electrically coupled).
[0003] Other embodiments of the invention are also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Illustrative and presently preferred embodiments of the
invention are illustrated in the drawings, in which:
[0005] FIG. 1 illustrates a first exemplary embodiment of a method
for printing conductive thickfilms over thickfilm dielectrics;
[0006] FIGS. 2 & 3 illustrate a first exemplary application of
the FIG. 1 method;
[0007] FIG. 4 illustrates a second exemplary application of the
FIG. 1 method;
[0008] FIG. 5 illustrates a third exemplary application of the FIG.
1 method;
[0009] FIG. 6 illustrates a first exemplary method for producing a
microwave circuit; and
[0010] FIG. 7 illustrates a second exemplary method for producing a
microwave circuit.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0011] FIG. 1 illustrates a method 100 for printing conductive
thickfilms over thickfilm dielectrics. The method 100 commences
with the printing 102 of a plurality of thickfilm dielectric layers
on a substrate, with each successive layer being printed over a
previous layer, and with each layer having sloped walls. After
printing a first subset of the plurality of thickfilm dielectric
layers, a first conductive thickfilm is printed 104 over at least
the walls of the first subset of dielectric layers. After printing
a second subset of the plurality of thickfilm dielectric layers, a
second conductive thickfilm is printed 106 over the second subset
of dielectric layers (with the first and second conductive
thickfilms being electrically coupled).
[0012] The method 100 is advantageous in that it provides for
building thicker (taller) transmission line structures, yet allows
conductive thickfilms to be printed over subsets of dielectrics
that are below a thickness that can be handled by current thickfilm
printing techniques. These advantages, in turn, enable transmission
line structures to be built with wider conductors. Wider conductors
might be needed for a variety of reasons. For example, and as
briefly mentioned in the Background of the Invention, an engineer
may want to couple a shunt component into a portion of a
transmission line structure, and the mounting mechanism of the
shunt component may require a wider conductor mounting area than
was achievable using prior thickfilm printing techniques.
[0013] A first application of method 100 is shown in FIGS. 2 &
3. FIG. 2 illustrates a substrate 200 having a ground plane 202
thereon. A first subset of thickfilm dielectric layers 204, 206 is
formed on the ground plane 202. A conductive thickfilm 208 is
printed on at least the walls of the dielectrics 204, 206 and is
electrically coupled to the ground plane 202. Alternatively, and as
shown in the figure, the conductive thickfilm 208 may be printed
over other portions of the dielectrics 204, 206 (e.g., over the top
surface of the dielectrics), and a conductor 210 may then be formed
by etching the conductive thickfilm 208.
[0014] To minimize irregularities in the conductor 210, the top
surface of the dielectric 206 may be polished. The dielectric 206
may also be polished to control the combined thickness of the first
subset of dielectrics 204, 206. The lower dielectric 204 need not
be polished.
[0015] The conductive thickfilm 208 may extend up any portion of
the walls of the dielectrics 204, 206. However, it is preferred
that the conductive thickfilm 208 extend up and onto the top
surface of the dielectric 206 so that it may be easily overprinted
by a next printing of conductive thickfilm.
[0016] FIG. 3 shows the structure of FIG. 2 after a second subset
of thickfilm dielectrics layers 300 has been printed over the first
subset 204, 206. It should be noted that although the exemplary
application shown in FIGS. 2 & 3 shows two layers 204, 206 in
the first subset of dielectric layers and one layer 300 in the
second subset of dielectric layers, each of the subsets could
alternately comprise one, two or any number of layers, so long as
the thickness of each subset is below that which may be printed by
current thickfilm printing processes.
[0017] If it is desired to adjust the combined thickness of the
second subset of dielectrics 300 may be polished. Thereafter, a
second conductive thickfilm 302 is printed over the second subset
of dielectrics such that the second conductive thickfilm 302 is
electrically coupled to the first conductive thickfilm 208.
[0018] A second application of method 100 is shown in FIG. 4. In
FIG. 4, a conductor 400 is printed below all of the dielectric
layers 402, 404, 406, and first and second conductive thickfilms
408, 410 are printed on subsets of the dielectric layers 402/404,
406. If desired, a ground plane 412 could be formed on the bottom
surface of a substrate 414, and vias and/or plated edges of the
substrate could be used to electrically couple the ground plane 412
to the conductive thickfilms 408, 410.
[0019] A third application of method 100 is shown in FIG. 5. FIG. 5
shows the same structures as FIG. 3, but with a shunt component 500
coupled to the conductor 210. By way of example, the shunt
component 500 could be a diode or capacitor. In areas where shunt
components are coupled to a transmission line structure, the top
dielectric 300 and shielding 302 of the structure may need to be
dispensed with. If a low loss dielectric like a KQ dielectric is
used for the lower dielectrics, conductor loss in areas where shunt
components are attached is dominated by conductor line width.
[0020] As will be understood by one of ordinary skill in the art, a
plurality of thickfilm dielectric layers may comprise additional
subsets of dielectric layers, each subset of which may be formed
under, over or between the first and second subsets referenced in
method 100, and of which may be printed with additional conductive
thickfilms.
[0021] As will also be understood by one of ordinary skill in the
art, a conductor need not be formed at its "maximum width" for its
entire length. That is, in areas where there is a need to have a
wider line width (e.g., because a shunt component needs to be
attached), a conductor may be formed wider, and in other areas the
conductor may be formed narrower.
[0022] By way of example, the substrates shown in the figures may
be ceramic substrates (e.g., lapped alumina ceramic substrates),
glass substrates, metallic substrates or polymer substrates. Also,
by way of example, the dielectric layers shown may be glass
dielectrics such as KQ dielectrics, or other dielectrics with
suitable microwave properties. KQ dielectrics are manufactured by
Heraeus Cermalloy (24 Union Hill Road, West Conshohocken, Pa.,
USA), and one such dielectric is KQ CL-90-7858 dielectric. By way
of further example, the conductors, conductive thickfilms and
ground planes shown in the figures may be formed of DuPont QG150
gold (available from DuPont (1007 Market Street, Wilmington, Del.,
USA)).
[0023] Using a 96% alumina ceramic substrate, KQ CL-90-7858
dielectric, and DuPont QG150 gold, the third application of method
100 (FIGS. 2 & 3) has been used to print approximately 5 mil
thick dielectric layers 204, 206, 300. The first subset 204, 206 of
these layers has then been polished to 10 mils, and a conductor 210
that is 21.4 mils wide, with an impedance of 50 Ohms, has been
formed. A typical shunt component 500 having dimensions of 20
mil.times.20 mil was able to be mounted on the conductor 210.
[0024] Variations and alternatives to the above methods for forming
microwave transmission line structures are disclosed in U.S. Pat.
No. 6,255,730 of Dove, et al. entitled "Integrated Low Cost Thick
Film RF Module", United States patent application of Casey, et al.
entitled "Methods for Making Microwave Circuits" (Ser. No.
10/600,143 filed Jun. 19, 2003), United States patent application
of Casey, et al. entitled "Methods for Depositing a Thickfilm
Dielectric on a Substrate" (Ser. No. 10/600,600 filed Jun. 19,
2003), and United States patent application of Casey, et al.
entitled "Methods for Forming a Conductor on a Dielectric" (Ser.
No. 10/601,042 filed Jun. 19, 2003), all of which are hereby
incorporated by reference. It should be noted that the term
"layer", as used herein, is intended to include not only a layer
printed in one step, but also a layer printed in multiple steps, as
disclosed in the patent applications of Casey, et al.
[0025] FIG. 6 illustrates a first exemplary method 600 for
producing a microwave circuit. The method 600 comprises printing
602 a plurality of thickfilm dielectric layers on a substrate, with
each successive layer being printed over a previous layer, and with
each layer having sloped walls. After printing a first subset of
the plurality of thickfilm dielectric layers, a first conductive
thickfilm is printed 604 over the first subset of dielectric
layers. The first conductive thickfilm is then etched 606 to form
i) a conductor on a surface of the first subset of dielectric
layers and ii) a ground on walls of the first subset of dielectric
layers. After printing a second subset of the plurality of
thickfilm dielectric layers over the conductor, a second conductive
thickfilm is printed 608 over the second subset of dielectric
layers (such that the second conductive thickfilm is electrically
coupled to the ground walls on the first subset of dielectric
layers).
[0026] FIG. 7 illustrates a second exemplary method 700 for
producing a microwave circuit. The method 700 comprises forming 702
a conductor on a substrate, and then printing 704 a plurality of
thickfilm dielectric layers over the conductor. Each successive
layer of thickfilm dielectric is printed over a previous layer, and
each layer has sloped walls. After printing a first subset of the
plurality of thickfilm dielectric layers, a first conductive
thickfilm is printed 706 over at least the walls of the first
subset of dielectric layers. Then, after printing a second subset
of the plurality of thickfilm dielectric layers, a second
conductive thickfilm is printed 708 over the second subset of
dielectric layers (such that the first and second conductive
thickfilms are electrically coupled).
[0027] While illustrative and presently preferred embodiments of
the invention have been described in detail herein, it is to be
understood that the inventive concepts may be otherwise variously
embodied and employed, and that the appended claims are intended to
be construed to include such variations, except as limited by the
prior art.
* * * * *